1. Field of the Invention
This invention relates to the field of precision liquid dispensing, such as when it is desirable or required to account by unit volume for all liquid dispensed. One such application is the dispensing of controlled substances in a clinical environment.
2. Description of the Background Art
Currently, controlled substance dispensing systems draw liquid directly from a bottle in which the material is supplied by the manufacturer. This is accomplished by intaking liquid through a dip tube that has been inserted through the bottle opening or cap with the bottle standing upright or fixtured at a slight angle. As dosages are dispensed, the material is drawn from the bottle until the level drops below the intake of the dip tube at which time air is suctioned into the dispensing system, the pumping device loses it's prime and dispensing ceases. At this point a partial dose has been dispensed and it, along with the residual liquid left in the bottle, must be accounted for. Weighing these leftover amounts, and covering the weight to the proper unit/volume using the material's specific gravity, is required.
After accounting for the partial dose and the residual liquid left in the bottle, the empty bottle must be replaced with a new full one. Because the pumping device has lost it's liquid prime after emptying the previous bottle, it is necessary to prime the system with the liquid from this new bottle. In doing so a certain amount of the liquid from this new bottle will be expelled from the dispense nozzle and must be collected, weighed and accounted for as previously described.
The shortfalls of the aforementioned system is the awkwardness of collecting, weighing and accurately accounting for the liquid lost to the partial dose and the residual liquid left in the bottle that cannot be fully drained, as well as the need to prime the system after each bottle change. Additionally, it should be understood that this is an entirely manual system and the reliance on human operation in material handling, weighing and data collection interjects many opportunities for inaccuracy and error.
There remains a need in the art for improvements in liquid dispensing and control systems.